Raphael josia



UNITED ST TES PATENT OFFICE.

RAPHAEL JUSIA, ()I FLORENCE, ITALY, ASSIGNOR TO WILLIAM REY AND C. DE VARIGNY, BOTH OF PARIS, FRANCE.

COMPOSITION FOR TREATING SULPHATES F LIME FOR THE MANUFACTURE OF ARTiFlClAL MARBLE SPECIFICATION forming part of Letters Application filed August 0, 1852.

To all whom it may concern:

Be it known that I, RAPHAEL J ()SIA, of Florence, Kingdom of Italy, have invented or discovered a new and useful Improvementin Oompositions for Treating Sulphates of Lime for the Manufacture of Artificial Marble; and I do hereby declare the following to be a full, clear, concise, and exact description thereof.

In an application for Letters Patent ot' the United States filed March 2, 1882, I have described and made claim to an improved process of treating or preparing gypsum (calcic sulphate or sulphate of lime) in the making of articles ofamaterial which I have termet certaldite without pulverization of the gypsum. In said application I described briefly certain of the compounds or compositions which I employ to produce certain effects and the manner of using them, but stated that separate applications would be made for patents for such compositions.

The present application relates to one of the compositions so referred to, and it is designed for use in the process herein described in the making of yellow certalditc.

In carrying out the process referred'to a suitable piece of gypsum (calcic sulphate) is first formed into the desired shape, or approximately such, by the use of suitable wellknown tools. The gypsum employed may be the ordinary native gypsum of commerce, though I prefer that which is comparatively pure or free from other matters of different composition. Such gypsum is usually obtained hydrated, or containing a certain percentage of waterin its composition; and the second step in the operation has reference to depriving the gypsum under treatment of a considerable part or the whole of such water. This is done by subjecting it to the action of a gradually-increasing heat, varying by preference with the size and quality of the material from 260 to 300 Fahrenheit, for about twelve hours, or until the desired partial or complete dehydration is obtained. The length of time as well as the degree of heat required to efiect this result will vary somewhat; with the size, character, and purity of the gypsum employed; but the temperature should not exceed 500 Fahrenheit,

Patent No. 265,508, dated October 3, 1882.

(No specimens.)

and both it and the time of exposure should be regulated and limited with reference to securing uniformity of treatment throughout the whole mass or body. This operation may be known to be complete when a fracture of a testblock presents a uniform white color. Any suitable drying or baking apparatus may be employed tor this purpose, many such being known in kindred branches of the arts; butit should be of such construction that the material under treatment shall not be brought into direct contact with the tire. When the desired dehydration has been effected the furnace is allowed to cool gradually, in order that the material under treatment may be cooled gradually; or the material may be removed with due care to prevent breakingand exposure to moisture, and allowed to cool outside the furnace gradually until it is reduced in temperature sufficiently to permit handling with safety in its subsequent treatment, which is designed to impart to it the dcsirrd color or tint and a high degree of insolubility and hardness thronghoutits mass. This step involves the use of the composition which forms the subject-matter of invention in the present application. This composition is formed'ot' thefollowing elements: water, by weight, two hund red parts; alum, by weight, four to five parts; oxalic acid, by weight, two to two and a half parts; logwood, by weight, four to six parts. These ingredients, being mixed in about the proportions named, form a solution which is used as a bath, and to this end a suitable quantity of it is placed in a vessel ofproper shape to receive the article to be treated,which is dipped or immersed in the bath and subjected to its action until the article has acquired the desired degree of hardness and color. The length of time required to effect this result will depend somewhat on the strength of the ingredients composing the bath or solution, the porosity and nature or physical and chemical condition of the article; but usually twelve hon-rs (more or less) will suffice, though to secure uniformity of treatment and of result through the whole body or mass of the article I prefer repeated dippings two, three, or more-say two or three seconds at first, and increasing gradually to one, two, or three or more minutes, more or less, with drying intervals of like increasing length between dippings, for half or three quarters of an hour or so, after which the article may remain in the bath for twelve hours or so.

\Vhile I do not limit my invention by any particular theory of chemical or physical reacllOllS involved in the use of this bath as above described, I believe with my present knowledge, that the salt (alum) held in solution, by taking the place of the molecules of water displaced by the previous dehydrated operation, acts chemically or physically upon the calcic sulphate, and renders it more compact, harder, and less soluble, and that the oxalic acid of the bath acts chemically or physically upon the impurities or matters of other composition, (carbonates, &c.,) which are usually contained in greater or less quantities in native gypsums, and produces a like indurating effect upon them, though the salt may also have an indurating action upon theimpurities present, and the acid may act in like manner. more or less upon the calcic sulphate. lhe logwood in the bath acts as a coloring agent, and by varying the proportion employed, as above indicated, it imparts to the article under treatment a yellow color or tint, not alone upon its surface, but dili'used through its mass, though lines, veins, and markings of darker shades will usually appear, which are due probably to the impurities present in the calcic sulphate. A highly-ornamental and beautifully-variegated color is thus secured, as well as such a degree of hardness, density, and insolubility as renders the article an excellent substitute for marble, ornamental stones, tiles, and other materials of kindred nature in the various uses to which they are applied in the arts.

When the article has been treated in the bath as above described it is removed and dried by exposure to the sun or to an equivalent furnace heat i'or one or two hours, or by ordinary atmospheric exposure for two or three days, when it is ready for polishing and such other manipulation as may best lit itt'or its intended use, which may be done by any of the methods practiced in kindred arts.

No claim is made herein to the process set forth, as that, with various modifications ot' the same, as circumstances may require, forms the subject-matter of the first application herein referred to. Neither do I limit my present in vention to the particular way herein described of applying it, though I now believe this way or process to be the best. I also believe the proportions of ingredients which I have named in forming my improved composition to be the best for the purposes stated, and, ainongo thers, to secure a uniform degree of hardness and color throughout the mass of the article. It the solution be very strong, there is great danger of rendering the surface of the article hard very quickly, and thereby preventing properaction of the bath upon the interior substance of the article; or if the solution be very weak too much time is required, and even then a proper degree of hardness, density,and insolubility is not secured; also, by the conjoint action-oi all the elements of the bath much better results are secured, especially upon native gypsums, than by a solution formed of a part otthe elements. For these reasons I prefer to employ all the elements of the composition 'in substantially the proportions named; but such limits, though the best, may be varied somewhat and still attain good results under skillful manipulation, and all such modifications which employ the elements substantially as herein described in about the proportions set forth I consider as coming within my invention and claim.

1 claim as my invention The composition herein described for treating dehydrated gypsum, consisting substantially of the following elements: water, alum, oxalic acid, and logwood, in about the propertions set forth.

In testimony whereof I have hereunto set my hand.

RAPHAEL JOSIA.

Witnesses:

GUiDo PAN'LALIONY, R. H. WIirr'rLEsEY. 

